Clues to improving farm productivity one agronomic survey at a time

10 November, 2014 by (comments)

Another step forward in addressing the yield gap

What are the low hanging fruit in reducing yield gaps and enhancing food security? Well it may not be fruit, per se, but basic techniques farmers can practice. A new CIAT-led publication presents an agronomic survey methodology which does just that – it presents a basket of options for boosting farm productivity which farmers can adapt to their social and economic context.

The farm-level agronomic survey assesses crop yields, and most importantly, points to some of the factors affecting yields in a field site in Babati District, Northern Tanzania.

How farmers manage their fields, and implications for how these management practices affect subsequent yields – for example applying manure, are some of the questions CIAT researchers are trying to answer.

If you are imagining fields of perfectly manicured, monocropped maize, think again! This study was conducted in 117 farmers’ fields where maize was inter cropped with nitrogen-fixing pigeon pea following small-holder farmer’s usual management and production practices.

Farmer Wema Ako in Babati, Tanzania examines the yield of his recent maize harvest.

Basic stepping stones to improved yield

One major finding is the significant variation in yields across fields. Huge deviations can be found on fields or within field plots only seven meters apart, with potential yield gaps of up to 7.4 tons per hectare revealed – that’s a wide gap!

Factors significantly influencing yield include delayed planting, the slope of the field, plant density, distance of the field from the homestead, crop variety, and the period of time that the field had been farmed, which influences soil fertility.

The difference in yield between flat and steep slopes was up to 1.6 tons per hectare – the equivalent of the yearly maize consumption of 10 Tanzanians. Low planting density is perhaps the most important factor influencing yield: Each additional plant in a field increases yield by 31 grams – a figure which will add up quickly if farmers are able to plant hundreds of additional plants per hectare. Based on the huge variation in plant density observed in the study, there is great potential for farmers to plant more crops per field.

Researchers suggest that lower yields with each year of cultivation and slope steepness are evidence of the continuous deterioration of soil and land health. They suggest some conservation measures on steep slopes – perhaps multipurpose forage and fodder crops to stabilize soil and mitigate further degradation.

The high yields some farmers achieved indicate that productivity can be improved with awareness, good management, and available resources to change practices.

Recommendations also include use of integrated soil fertility management (ISFM) principles – including using appropriate varieties, taking note of recommended planting date and density, and application of suitable levels of mineral and organic fertilizers.

A farmer in Babati region Tanzania explains his management techniques for this field of intercropped maize to local extension and CIAT staff.

Remembering the bigger picture

Despite these immediate options to increase farm productivity – such as increasing manure application, and adopting appropriate varieties – the whole story is, of course, more complex.

For every kilometer a farmer’s plot is further away from the home, yield decreased by 286 kilogram (kg) per hectare. This is logical because more effort and time has to be put into reaching farther fields; however it has implications on opportunities for improving productivity and could result in neglected and degraded land.

Every year, land under cultivation decreased yields by 18 kg per hectare. Considering the negative nutrient balances for the essential macronutrients nitrogen, phosphorous and potassium, the finding raises questions about farmers mining the nutrients from their soils, where they are not replaced.

Armed with this information, we can figure out the best ways to work with farmers to reduce their yield gaps where possible. In future, as the authors themselves state: “Strategies are needed to reduce these yield gaps while still addressing sustainability issues of the production base.” They call for the “need to think of holistic approaches to address all yield limiting factors in farmer fields.”

Future research could build upon these findings by taking into account the social and economic situation of farmers – and why farmers manage their fields in a specific way – for a more comprehensive farm gap approach that puts farmer decision-making at the center of research in development.

CIAT researchers will continue to ask these questions and seek the best ways to put the results into action. If we gain insights into what influences yield gaps and why, we can generate better site-specific recommendations and more targeted further research to improve farm productivity.

The publication by CIAT scientists Job Kihara and Lulseged Desta, and colleagues from IITA and SARI – Agronomic survey to assess crop yield, controlling factors and management implications: a case-study of Babati in northern Tanzania – is free to download from the Journal of Nutrient Cycling and Agroecosystems.

This study was sponsored by IITA through the USAID Feed the Future’s Africa RISING Program.

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Filed Under: Africa @en, Regions, Soils